AME 52:159-173 (2008)  -  DOI:

Fate of dimethylsulfoniopropionate (DMSP) during the decline of the northwest Atlantic Ocean spring diatom bloom

Martine Lizotte1,*, Maurice Levasseur1, Michael G. Scarratt2, Sonia Michaud2, Anissa Merzouk3, Michel Gosselin4, Julien Pommier4,5

1Québec-Océan, Département de Biologie, Université Laval, Québec, Québec G1V 0A6, Canada
2Maurice Lamontagne Institute, Fisheries and Oceans Canada, 850 route de la Mer, CP 1000, Mont-Joli, Québec G5H 3Z4, Canada
3Earth and Ocean Sciences/Oceanography, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
4Institut des sciences de la mer (ISMER), Université du Québec à Rimouski, 310 allée des Ursulines, Rimouski, Québec G5L 3A1, Canada
5Groupe de Recherche sur les Écosystèmes Aquatiques, Département de Chimie-Biologie, Université du Québec à Trois-Rivières, Québec G9A 5H7, Canada

ABSTRACT: A 7 d Lagrangian process study of the biogeochemical cycling of dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) was conducted within a decaying diatom bloom in the northwest Atlantic Ocean in spring 2003. Ambient profiles of DMSP and DMS were surveyed daily in the water column and were used to estimate in situ net transformation rates. Phytoplankton and bacterioplankton abundance were determined within the surface mixed layer (SML) as well as at the deep chlorophyll maximum (DCM), and sinking fluxes of particulate DMSP (DMSPp) below 75 to 100 m were assessed using free-drifting particle interceptor traps. Chlorophyll a (chl a) concentration and diatom abundance declined in the SML over the course of the study period, and the phytoplankton chl a biomass progressively settled above the nitracline forming the DCM. The decline of the diatom bloom coincided with the settling of DMSPp out of the SML and the formation of a DMSP-rich layer at the DCM. The low daily sinking loss rate of DMSPp at 75 m (<2% d–1) provided confirmation of the efficient retention of DMSPp at the DCM. The decaying bloom gave rise to an initial release of dissolved DMSP (DMSPd) in the upper water column, which was rapidly consumed by the growing bacterial community. The rapid loss of DMSPd was accompanied by significant increases in net production of DMS in the SML and fluxes of DMS to the atmosphere. Despite this increase in DMS dynamics, overall in situ net production rates remained fairly low during the 7 d period (≤0.4 nmol DMS l–1d–1), suggesting that demethylation by the developing bacterial community dominated DMSPd-consuming processes.

KEY WORDS: DMSP distribution · DMS production · Diatom bloom · Lagrangian study · Sinking flux · Northwest Atlantic

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Cite this article as: Lizotte M, Levasseur M, Scarratt MG, Michaud S, Merzouk A, Gosselin M, Pommier J (2008) Fate of dimethylsulfoniopropionate (DMSP) during the decline of the northwest Atlantic Ocean spring diatom bloom. Aquat Microb Ecol 52:159-173.

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